Your mattress is an RV (short) queen size. That will limit your choices, because not a lot of manufacturers make mattresses in that size. Also, expect to pay a premium, because the short queen mattresses are not made in the same volume as the standard queens.
I got one of these https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
several years ago, and I'm quite happy with it.
Retired electronics engineer. Avid paddler & birder.
2011 Silverado 2500HD, diesel, 4x4,crew cab, 8' bed
Palomino Puma 253FBS (27' 5er) & '94 19' Class B